/*
 * @BEGIN LICENSE
 *
 * Psi4: an open-source quantum chemistry software package
 *
 * Copyright (c) 2007-2025 The Psi4 Developers.
 *
 * The copyrights for code used from other parties are included in
 * the corresponding files.
 *
 * This file is part of Psi4.
 *
 * Psi4 is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, version 3.
 *
 * Psi4 is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License along
 * with Psi4; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * @END LICENSE
 */

/*! \file
    \ingroup CCDENSITY
    \brief Enter brief description of file here
*/
#include "psi4/libiwl/iwl.h"
#include "psi4/libdpd/dpd.h"
#include "psi4/psifiles.h"

#include "MOInfo.h"
#include "Params.h"
#include "Frozen.h"
#define EXTERN
#include "globals.h"

#include <cstdio>

namespace psi {
namespace ccdensity {

/* DEANTI_RHF(): Convert the RHF two-particle density from an
** energy expression using antisymmetrized Dirac integrals to one
** using simple Diract integrals. The original, Fock-adjusted
** density (see the comments in fock.c) corresponds to a
** two-electron energy (or energy derivative) expression of the
** form:
**
** E(TWO) = 1/4 sum_pqrs Gpqrs <pq||rs>
**
** However, the derivative two-electron integrals are produced in
** Mulliken-ordered, symmetric form rather than Dirac-ordered
** antisymmetric form.  This code alters the two-particle density
** matrix ordering for the energy expression of the form:
**
** E(TWO) = 1/2 sum_pqrs Gpqrs <pq|rs>
**
** The final conversion to Mulliken ordering is taken care of in
** dump.c
**
** The second equation above may be derived via
**
** E(TWO) = 1/4 sum_pqrs Gpqrs (<pq|rs> - <pq|sr>)
**        = 1/4 sum_pqrs Gpqrs <pq|rs> - 1/4 sum_pqrs Gpqrs <pq|sr>
**        = 1/4 sum_pqrs Gpqrs <pq|rs> - 1/4 sum_pqrs Gpqsr <pq|rs>
**        = 1/4 sum_pqrs (Gpqrs - Gpqsr) <pq|rs>
**        = 1/2 sum_pqrs Gpqrs <pq|rs>
**
** Equations for the individual components are given explicitly in
** comments below.
** */

void deanti_RHF(const struct RHO_Params& rho_params) {
    dpdbuf4 G1, G2;
    dpdfile2 D, F;
    double one_energy = 0.0, two_energy = 0.0, total_two_energy = 0.0;
    dpdbuf4 A, B, C, DInts, E, FInts;

    if (!params.aobasis && params.debug_) {
        outfile->Printf("\n\tEnergies re-computed from Mulliken density:\n");
        outfile->Printf("\t-------------------------------------------\n");

        global_dpd_->file2_init(&D, PSIF_CC_OEI, 0, 0, 0, rho_params.DIJ_lbl);
        global_dpd_->file2_init(&F, PSIF_CC_OEI, 0, 0, 0, "h(i,j)");
        one_energy += 2.0 * global_dpd_->file2_dot(&D, &F);
        global_dpd_->file2_close(&F);
        global_dpd_->file2_close(&D);

        global_dpd_->file2_init(&D, PSIF_CC_OEI, 0, 1, 1, rho_params.DAB_lbl);
        global_dpd_->file2_init(&F, PSIF_CC_OEI, 0, 1, 1, "h(a,b)");
        one_energy += 2.0 * global_dpd_->file2_dot(&D, &F);
        global_dpd_->file2_close(&F);
        global_dpd_->file2_close(&D);

        global_dpd_->file2_init(&D, PSIF_CC_OEI, 0, 0, 1, rho_params.DIA_lbl);
        global_dpd_->file2_init(&F, PSIF_CC_OEI, 0, 0, 1, "h(i,a)");
        one_energy += 2.0 * global_dpd_->file2_dot(&D, &F);
        global_dpd_->file2_close(&F);
        global_dpd_->file2_close(&D);

        global_dpd_->file2_init(&D, PSIF_CC_OEI, 0, 0, 1, rho_params.DAI_lbl);
        global_dpd_->file2_init(&F, PSIF_CC_OEI, 0, 0, 1, "h(i,a)");
        one_energy += 2.0 * global_dpd_->file2_dot(&D, &F);
        global_dpd_->file2_close(&F);
        global_dpd_->file2_close(&D);

        outfile->Printf("\tOne-electron energy        = %20.15f\n", one_energy);
    }

    /* E_ijkl = (2 Gijkl - Gijlk) <ij|kl> */
    global_dpd_->buf4_init(&G1, PSIF_CC_GAMMA, 0, 0, 0, 0, 0, 0, "GIjKl");
    global_dpd_->buf4_scmcopy(&G1, PSIF_CC_GAMMA, "2 Gijkl - Gijlk", 2);
    global_dpd_->buf4_sort_axpy(&G1, PSIF_CC_GAMMA, pqsr, 0, 0, "2 Gijkl - Gijlk", -1);
    global_dpd_->buf4_close(&G1);

    global_dpd_->buf4_init(&G1, PSIF_CC_GAMMA, 0, 0, 0, 0, 0, 0, "2 Gijkl - Gijlk");
    global_dpd_->buf4_copy(&G1, PSIF_CC_GAMMA, "GIjKl");

    if (!params.aobasis && params.debug_) {
        global_dpd_->buf4_init(&A, PSIF_CC_AINTS, 0, 0, 0, 0, 0, 0, "A <ij|kl>");
        two_energy = global_dpd_->buf4_dot(&A, &G1);
        global_dpd_->buf4_close(&A);
        outfile->Printf("\tIJKL energy                = %20.15f\n", two_energy);
        total_two_energy += two_energy;
    }
    global_dpd_->buf4_close(&G1);

    /* E_ijka = 2 [ (2 Gijka - Gjika) <ij|ka> ] */
    /* NB: GIjKa is scaled by 1/2 in Gijka.cc. */
    global_dpd_->buf4_init(&G1, PSIF_CC_GAMMA, 0, 0, 10, 0, 10, 0, "GIjKa");
    global_dpd_->buf4_scmcopy(&G1, PSIF_CC_GAMMA, "2 Gijka - Gjika", 2);
    global_dpd_->buf4_sort_axpy(&G1, PSIF_CC_GAMMA, qprs, 0, 10, "2 Gijka - Gjika", -1);
    global_dpd_->buf4_close(&G1);

    global_dpd_->buf4_init(&G1, PSIF_CC_GAMMA, 0, 0, 10, 0, 10, 0, "2 Gijka - Gjika");
    /* The factor of 2 here is necessary because Gijka is multiplied by 1/2 in Gijka.cc */
    global_dpd_->buf4_scmcopy(&G1, PSIF_CC_GAMMA, "GIjKa", 2);
    if (!params.aobasis && params.debug_) {
        global_dpd_->buf4_init(&E, PSIF_CC_EINTS, 0, 0, 10, 0, 10, 0, "E <ij|ka>");
        two_energy = global_dpd_->buf4_dot(&E, &G1);
        global_dpd_->buf4_close(&E);
        /* The factor of 4 here is necessary because Gijka is multiplied by 1/2 in Gijka.cc */
        outfile->Printf("\tIJKA energy                = %20.15f\n", 4 * two_energy);
        total_two_energy += 4 * two_energy;
    }
    global_dpd_->buf4_close(&G1);

    /* E_ijab = [ (2 Gijab - Gijba) - GIBJA - GIbjA ] <ij|ab> */
    global_dpd_->buf4_init(&G1, PSIF_CC_GAMMA, 0, 0, 5, 0, 5, 0, "GIjAb");
    global_dpd_->buf4_scmcopy(&G1, PSIF_CC_GAMMA, "2 Gijab - Gijba", 2);
    global_dpd_->buf4_sort_axpy(&G1, PSIF_CC_GAMMA, pqsr, 0, 5, "2 Gijab - Gijba", -1);
    global_dpd_->buf4_close(&G1);

    global_dpd_->buf4_init(&G2, PSIF_CC_GAMMA, 0, 10, 10, 10, 10, 0, "GIBJA");
    global_dpd_->buf4_sort_axpy(&G2, PSIF_CC_GAMMA, prsq, 0, 5, "2 Gijab - Gijba", -1);
    global_dpd_->buf4_close(&G2);
    global_dpd_->buf4_init(&G2, PSIF_CC_GAMMA, 0, 10, 10, 10, 10, 0, "GIbjA");
    global_dpd_->buf4_sort_axpy(&G2, PSIF_CC_GAMMA, prsq, 0, 5, "2 Gijab - Gijba", -1);
    global_dpd_->buf4_close(&G2);

    global_dpd_->buf4_init(&G1, PSIF_CC_GAMMA, 0, 0, 5, 0, 5, 0, "2 Gijab - Gijba");
    global_dpd_->buf4_scmcopy(&G1, PSIF_CC_GAMMA, "GIjAb", 2);
    if (!params.aobasis && params.debug_) {
        global_dpd_->buf4_init(&DInts, PSIF_CC_DINTS, 0, 0, 5, 0, 5, 0, "D <ij|ab>");
        two_energy = 2.0 * global_dpd_->buf4_dot(&DInts, &G1);
        global_dpd_->buf4_close(&DInts);
        outfile->Printf("\tIJAB energy                = %20.15f\n", two_energy);
        total_two_energy += two_energy;
    }

    global_dpd_->buf4_close(&G1);

    /* G'_IbJa = 2 GIBJA + 2 GIbJa */
    global_dpd_->buf4_init(&G1, PSIF_CC_GAMMA, 0, 10, 10, 10, 10, 0, "GIbJa");
    global_dpd_->buf4_init(&G2, PSIF_CC_GAMMA, 0, 10, 10, 10, 10, 0, "GIBJA");
    global_dpd_->buf4_axpy(&G2, &G1, 1);
    global_dpd_->buf4_close(&G2);
    //  dpd_buf4_scm(&G1, 2);
    if (!params.aobasis && params.debug_) {
        global_dpd_->buf4_init(&C, PSIF_CC_CINTS, 0, 10, 10, 10, 10, 0, "C <ia|jb>");
        two_energy = 2.0 * global_dpd_->buf4_dot(&C, &G1);
        global_dpd_->buf4_close(&C);
        outfile->Printf("\tIBJA energy                = %20.15f\n", two_energy);
        total_two_energy += two_energy;
    }

    global_dpd_->buf4_close(&G1);

    /* E_ciab = 2 [ (2 Gciab - Gciba) <ci|ab> ] */
    /* NB: Gciab is scaled by 1/2 in Gciab.cc. */
    global_dpd_->buf4_init(&G1, PSIF_CC_GAMMA, 0, 11, 5, 11, 5, 0, "GCiAb");
    global_dpd_->buf4_scmcopy(&G1, PSIF_CC_GAMMA, "2 Gciab - Gciba", 2);
    global_dpd_->buf4_sort_axpy(&G1, PSIF_CC_GAMMA, pqsr, 11, 5, "2 Gciab - Gciba", -1);
    global_dpd_->buf4_close(&G1);

    global_dpd_->buf4_init(&G1, PSIF_CC_GAMMA, 0, 11, 5, 11, 5, 0, "2 Gciab - Gciba");
    /* The factor of 2 here is necessary because Gciab is multiplied by 1/2 in Gciab.cc */
    global_dpd_->buf4_scmcopy(&G1, PSIF_CC_GAMMA, "GCiAb", 2);
    if (!params.aobasis && params.debug_) {
        global_dpd_->buf4_init(&FInts, PSIF_CC_FINTS, 0, 10, 5, 10, 5, 0, "F <ia|bc>");
        global_dpd_->buf4_sort(&FInts, PSIF_CC_FINTS, qpsr, 11, 5, "F <ai|bc>");
        global_dpd_->buf4_close(&FInts);
        global_dpd_->buf4_init(&FInts, PSIF_CC_FINTS, 0, 11, 5, 11, 5, 0, "F <ai|bc>");
        two_energy = global_dpd_->buf4_dot(&FInts, &G1);
        global_dpd_->buf4_close(&FInts);
        /* The factor of 4 here is necessary because Gciab is multiplied by 1/2 in Gciab.cc */
        outfile->Printf("\tCIAB energy                = %20.15f\n", 4 * two_energy);
        total_two_energy += 4 * two_energy;
    }

    global_dpd_->buf4_close(&G1);

    /* E_abcd = (2 Gabcd - Gabdc) <ab|cd> */
    global_dpd_->buf4_init(&G1, PSIF_CC_GAMMA, 0, 5, 5, 5, 5, 0, "GAbCd");

    global_dpd_->buf4_scmcopy(&G1, PSIF_CC_GAMMA, "2 Gabcd - Gabdc", 2);
    global_dpd_->buf4_sort_axpy(&G1, PSIF_CC_GAMMA, pqsr, 5, 5, "2 Gabcd - Gabdc", -1);
    global_dpd_->buf4_close(&G1);

    global_dpd_->buf4_init(&G1, PSIF_CC_GAMMA, 0, 5, 5, 5, 5, 0, "2 Gabcd - Gabdc");
    global_dpd_->buf4_copy(&G1, PSIF_CC_GAMMA, "GAbCd");
    if (!params.aobasis && params.debug_) {
        global_dpd_->buf4_init(&B, PSIF_CC_BINTS, 0, 5, 5, 5, 5, 0, "B <ab|cd>");
        two_energy = global_dpd_->buf4_dot(&B, &G1);
        global_dpd_->buf4_close(&B);
        outfile->Printf("\tABCD energy                = %20.15f\n", two_energy);
        total_two_energy += two_energy;
    }

    global_dpd_->buf4_close(&G1);

    if (!params.aobasis && params.debug_) {
        outfile->Printf("\tTotal two-electron energy  = %20.15f\n", total_two_energy);
        if (params.ground) {
            // outfile->Printf( "\tCCSD correlation energy    = %20.15f\n",
            //	  one_energy + total_two_energy);
            // outfile->Printf( "\tTotal CCSD energy          = %20.15f\n",
            //	  one_energy + total_two_energy + moinfo.eref);
            outfile->Printf("\t%7s correlation energy = %20.15f\n",
                            params.wfn == "CCSD_T" ? "CCSD(T)" : params.wfn.c_str(), one_energy + total_two_energy);
            outfile->Printf("\tTotal %7s energy       = %20.15f\n",
                            params.wfn == "CCSD_T" ? "CCSD(T)" : params.wfn.c_str(),
                            one_energy + total_two_energy + moinfo.eref);
        } else {
            outfile->Printf("\tTotal EOM CCSD correlation energy        = %20.15f\n", one_energy + total_two_energy);
            outfile->Printf("\tCCSD correlation + EOM excitation energy = %20.15f\n", moinfo.ecc + params.cceom_energy);
            outfile->Printf("\tTotal EOM CCSD energy                    = %20.15f\n",
                            one_energy + total_two_energy + moinfo.eref);
        }
    }
}

}  // namespace ccdensity
}  // namespace psi
